Rubber composition and method of preserving rubber



Patented July 4, 1933 UNITED STATES MARION o. REED, or SOUTH CHARLESTON,

WEST VIRGINIA, ASSIGNOR TO THE B. F.

GOODRIC H COMPAlN'Y, bl? NEW YORK, N. Y., A CORPORATION OF NEW YORK RUBBER COMPOSITION AND METHOD or PRESERVING RUBBER No Drawing. Original application filed November 4, 1929, Serial No. 404,865. Divided and this application filed April 27,

This invention relates to thel art'oii preserving rubber, either in the vulcanizedor unvulcanized condition, and to rubbercomposltions so preserved. 1 7

It is well known that rubber is subject to more or less rapid deterioration upon aging,

especially when. exposed to light, heat, or air. 'It has been proposed to treat rubber with so-called anti-oxidants or age-resisters for the purpose of retardingits deterioration and extending the period of its usefulness. Such previously known anti-oxidants include phenolic compounds, aromatic amino compounds, and the. condensation products ofaldehydes and amines.

This invention consists in'treating. rubber with a member of a new-class of age-resisters, the said classf' comprising secondary amines, one of the substituents of which is a monovalent aliphatic hydrocarbon group while the other is an aromatic group containing more than one aromatic ring. The aliphatic group may be any straight or branched chain aliphatic hydrocarbon group, or alicyclic group, and may evencontain aromatic rings remote from the point of attachment as in the benzyl group. The aromatic group may contain two or more aromatic rings, conjugated,--' adjacent or indirectly joined one to another. Thus, the'class includes such substances as: methyl-alphanaphthylamine, methyl beta naphthylamine, methyl-anthracylamine, I methylamino-v biphenyl, methylamino diphenylmethane,

l methylaminodiphenyl ether, p-methylaminodiphenylamine, N methyl-N-beta-naphthylp-phenylene diainine, p-methylamino-diphenyl p phenylene-diamine, 1 methylamino-e-naphthol, p-methylamino-phydrox'ydiphenyl ether, p,pdi-methylarnino diphenylamine, and the corresponding ethyl,- propyl butyl, amyl, heptyl, and other alkyl derivatives as well as similar compounds containing other substituent groups such as the cyclopentyl cyclohexyl, and benzyl and phe nyl-ethyl groups, which, although not strictly aliphatic in nature, undergothe characteristic reactions of and confer upon their compounds essentially the same properties as 1932. Serial No. 607,889.

purelyaliphatic groups; being understood that the above-named compounds are merely illustrative oi the scope of the class, and that many other related compounds are likewise included within the definition. Any one or a mixture of several of the above-mentioned" class of age-resistors may be incorporated into rubber ora rubber. composition with beneficial effects on its age-resisting properties, preferably from 0.2 to 5 parts by weight to 1.00Iparts of rubber being used.

Example l As a specific example of one embodiment of the method of this invention,

- (294 F-) to produce an optimum cure. The

rate of aging of the vulcanized composition was determined, by measuring its tensile,

strength and elongation before and after aging. The accelerated aging test was carried out in the Geer aging oven, in which samples were maintained at a tem erature oi 70 C. (158 F.) in a constantly renewed stream of air, the results being recorded in the following table, inwhich T indicates ultimate tensile strength in pounds per sq. inch and E indicates ultimate elongation in per cent. of original length:

Beiore After 2 After 5 After 7 aging days days days A similar composition without the methylalpha-naphthylamine deteriorated ap'proxi-;

mateiy twice as much'in the same time.

Example A rubber composition similar to. that specified in Example 1 above but without the methyl-alpha-naphthylamine Was divided intox5 portions, one of which Aging tests of alkyl-alpha-naphthylcmi'nes After 48 Before g Z 35 hours in I aglng Gear oven Bieit'gl-llgoavis Age-register (0.5%)

T E T E T E None (control) 3624 675 1792 440 ,839 362 EthyI-alpha-naphthylamine. 3588 673 2412 473 2387 570 2- isoamyl -alpha naphthy mine 3444 703 2952 640 2208 603 Cyclohexyl-elpba-naphthy1- amine 3471 677 1945 520 1438, 500 Benzyl-ulpha-naphthylamlne 3648 670 2680 573 2155 583 From the examples given above it is evident that secondary amines of the abovedescribed class, namely those possessing the general type formula B I!l--R2 where R is an alkyl group and R is an aryl group containing at least two armomatic rings, are extremely effective in retarding the deterioration which rubber normally undergoes upon aging.

Obviously, the practice of this invention is not limited to the specific compositions given above, such compositions being merely illustrative of one manner of employing the ageresisters of this invention. The proportions of the constituents may be varied, or other substances may be substituted therefor, since this invention is applicable to pure rubber or rubber compositions of the most varied nature. The age-resisters may also be applied to unvulcanized or vulcanized rubber with goodeifect on the age-resisting properties of the rubber, such as by applying them to the surface of the rubber, as for example in solution, or in the form of a paste or emulsion.

It is to be understood that the term treating as employed in the appended claims is used in a generic sense to include either the incorporation of the age-resistors into the rubber by milling or similar process, or their addition to the rubber latex before its coagulation, or the application thereof to the surface of a mass of crude or vulcanized rubber. The term rubber is likewise employed in the claims in a generic sense to include caoutchouc, whether natural or synthetic, reclaimed rubber, balata, gutta percha, rubber isomers and like products, whether or not admixed with fillers, pigments, vulcanizing 0r accelerating agents. The term aliphatic, unless otherwise limited, is to be understood as including all substituent groups which confer the characteristic properties of aliphatic compounds on their derivatives, as opposed to aromatic groups which confer different and distinctly aromatic properties on their derivatives, and particularly as including all groups hereinabove referred to as aliphatic in nature.

This application is a division of my copending application Serial No. lO-l,8(38 filed November 4, 1929.

lVhile I have herein disclosed certain preferred manners of performing my invention, I do not thereby desire or intend to limit myself solely thereto, for, as hitherto stated,

the precise proportions of the materials utilized may be varied andother materials having equivalent chemical properties may be employed if desired without departing from the spirit and scope of the invention as defined in the appended claims.

I claim 1. The method of preserving rubber which comprises treating rubber with a substance of the general formula H Brit-R.

where R is a cyclic aliphatic hydrocarbon group and R is an aromatic group containing at least two aromatic rings.

2. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a cyclic aliphatic hydrocarbon group and R is a diary] amine group.

4. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a benz yl group and R is an aromatic group containing two aromatic rings.

5. The method of preservingrubber which. comprises treating rubber with a substance of the general formula amine group.

6. The method of preserving rubber which comarises treatin rubber with -ben-Z lamino diphenylamine.

7. The method of preserving rubber which comprisestreating rubber with a substance of the general formula I where R is a cyclic aliphatic hydrocarbon group and R is an aromatlc group contaming at least two conjugated aromatic rings.

8. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a cycloparaffinic hydrocarbon group and R is an aromatic group containing at least two aromatic rings.

12. The method of preserving rubber which comprises treating rubber with a substance of the general formula R1-NRg where R is a cycloparaiiinic hydrocarbon group and R is an aryl hydrocarbon group containing two aromatlc rings.

13. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is a cycloparafiinic hydrocarbon group and'R is a naphthyl group.

14-. The method of preserving rubber which comprises treating rubber with a substance of the general formula where R is cyclohexyl group and R is an aromatic group containmg two aromatic rlngs.

' T5. The Incthod"*of preserving rubber which'co'mprises treating'rubber with a substance of the general formula where R is a cycloheXyl group and R is an aryl group containing at least two conjugated aromatic rings. I

16. The method of preserving rubber which comprises treating rubber with cycloheX-yl a-lpha-naphthylamine.

17. The method of preserving rubber which comprises vulcanizing a mixture of rubber, sulphur, an active organic accelerator, and a substance of the general formula R -Rg where R is a cyclic aliphatic hydrocarbon group and R is an aromatic group containing at least two aromatic rings.

18. The method of preserving rubber which comprises vulcanizing a mixture of rubber, sulphur, an active organic accelerator, and a substance of the general formula where R is a cyclohexyl group and R is an aryl hydrocarbon group containing two aromatic rings.

20. The method of preserving rubber which comprises vulcanizing a mixture of rubber, sulphur, an active organic accelerator, and a cyclohexyl naphthylamine.

21. A composition comprising rubber and a substance of the general formula 1 R1N- z where R is a cyclic aliphatic hydrocarbon group and R is an aromatic group containing two aromatic rings.

22. A composition comprising rubber and a substance of the general formula where R is a cyclic aliphatic hydrocarbon group and R is an aromatic group containing 1 two distinct aromatic rings.

23. A composition comprising rubber and a substance of the general formula where R is a benzyl group and R is an aromatic group containing two aromatic rings.

24. A composition comprising rubber and a substance of the general formula where R is a cyclic aliphatic hydrocarbon group and R is an aryl group consisting of two aromatic rings.

27. A composition comprising rubber and a substance of the general formula 8 lei-1L8.

where R is a cyclohexyl group and R, is an aromatic hydrocarbon group containing at least two aromatic rings.

28. A composition comprising rubber and a cyclohexyl naphthylamine.

29. A composition comprising rubber and a substance of the general formula Where R is a benzyl group and R is an aryl group containing at least two conjugated rings.

30. A composition comprising rubber and benzyl alpha-naphthylamine.

In witness whereof I have hereunto set my hand this 19th day of April, 1932.

MARION C. REED. 

